Traffic Surveys for the design of the road

Traffic Survey

1. Application of Low Volume Roads Manual APPLICATION OF LOW-VOLUME ROADS MANUAL Lesson 9: Traffic Surveys Eng. Lameck Methusela

2. 2 OUTLINE Application of Low Volume Roads Manual 2 Lesson 9: Traffic Surveys Why Traffic Survey Types of Traffic Surveys Classified Traffic Counts O-D Studies Axle Load Survey Methods of Classified Traffic Counts Duration of Traffic Counts Selection of Traffic Count Stations

3. 1. WHY TRAFFIC SURVEY Application of Low Volume Roads Manual 3 Geometric Design The volume and composition of traffic, both motorized and non-motorized, influence the cross section design (carriageway and shoulders). Pavement Design The deterioration of the pavement is influenced by both the magnitude and frequency of individual axle loads. Road Safety Measures The volume, type and characteristics of the traffic using the road all influence the type of road safety. Lesson 9: Traffic Surveys

4. Application of Low Volume Roads Manual 4 2. TYPES OF TRAFFIC SURVEYS Three types of traffic surveys are typically carried out: Classified Traffic Counts. Origin-Destination Studies. Axle Load Surveys. Lesson 9: Traffic Surveys

5. Application of Low Volume Roads Manual 5 2.1 Classified Traffic Counts One of the most important items of data for both geometric and pavement structural design planning purposes in terms of evaluating economic benefits derived from construction of LVRs. 2.1.1 Use of Traffic Data Lesson 9: Traffic Surveys

6. Application of Low Volume Roads Manual 6 2.1 Classified Traffic Counts volume and composition of current and future traffic in terms of motorcycles, cars, buses, light, medium, heavy and very heavy goods vehicles, non-motorized vehicles and pedestrians . 2.1.2 Traffic Classes Lesson 9: Traffic Surveys

7. Application of Low Volume Roads Manual 7 2.1.2 Traffic Classes Class Type Axles Description A Car 2 Passenger cars and taxis B Pick-up/4WD 2 Pick-up, minibus, SUV C Small Bus 2 ≤ 25 seats Light Traffic (Used in capacity analysis for geometric design) Lesson 9: Traffic Surveys

8. Application of Low Volume Roads Manual 8 Heavy Traffic/Commercial Vehicles (Used in capacity and axle load analysis for pavement design) Class Type Axles Description D Large Bus/Coach 2 > 25 seats E Light Goods Vehicle 2 ≤ 3.0 tons empty weight F Medium Goods Vehicle 2 > 3.0 tons empty weight G Heavy Goods Vehicle 3/4 > 3.0 tons empty weight H Very Heavy Goods Vehicle ≥ 4 > 3.0 tons empty weight I 2-Axle Trailer 2 Trailers towed by MGVs, HGVs or VHGVs J 3-Axle Trailer 3 K 4-Axle Trailer 4 L Tractor 2 Lesson 9: Traffic Surveys

9. Application of Low Volume Roads Manual 9 Motorcycles and non-motorized traffic (Used in capacity analysis for geometric design) Class Type Description M Motorcycles All motorcycles (2-wheelers and 3-wheelers) N Bicycles O Other NMT Animal/human drawn carts, etc P Pedestrians Lesson 9: Traffic Surveys

10. Application of Low Volume Roads Manual 10 2.2 Origin-Destination Survey Carried out to establish the nature of travel patterns in and around the area of enquiry. Normally carried out as part of a regional planning exercise rather than for an individual road project. These surveys, which can be quite labour -intensive, serve a number of useful purposes including quantitative assessment of the amount of traffic likely to be affected by the proposal consequent impacts on various elements in the road system. Lesson 9: Traffic Surveys

11. Application of Low Volume Roads Manual 11 2.3 Axle Load Surveys Done to obtain the average axle loading for each class of heavy traffic: Provide critical and essential information required for both cost-effective pavement design and preservation of existing roads. Notes: Conducted on existing roads with high expectance of capturing data for all commercial traffic classes Historic data may also be useful Lesson 9: Traffic Surveys

12. Application of Low Volume Roads Manual 12 2.3 Axle Load Survey Importance of this parameter is highlighted by the well-known “fourth power law” which exponentially relates increases in axle load to pavement damage. e.g. an increase in axle load of 20% produces an increase in damage of about 120% Lesson 9: Traffic Surveys

13. Application of Low Volume Roads Manual 13 3. CLASSIFIED TRAFFIC COUNT METHODS Three methods are commonly used : Manual Count Automatic Count Moving Observer Others include: Combination of Manual and Mechanical Methods Photographic Method Lesson 9: Traffic Surveys

14. Application of Low Volume Roads Manual 14 Notes: 24-hr counts used to estimate 12hr /24hr conversion factor Weekend 24-hr counts used to estimate weekend/weekday factor Peak season/Low season depending on timing of the counts 4. DURATION OF TRAFFIC COUNT Lesson 9: Traffic Surveys

15. Application of Low Volume Roads Manual 15 Two roads are planned to be upgraded to bitumen standard: 30km road A-B-C 9km access road B-D to plantation D Qn : Propose the number and location of traffic count stations B C D A Group Exercise 5. SELECTION OF COUNT STATIONS Lesson 9: Traffic Surveys

16. Application of Low Volume Roads Manual 16 A B C D Segment A-B: 1 station between A and B Segment B-C: 1 station between B and C Segment B-D: 1 Station between B and D Lesson 9: Traffic Surveys

17. Application of Low Volume Roads Manual 17 Thank you! Lesson 9: Traffic Surveys